Portable breathing devices are particularly useful in emergency situations. A typical portable breathing apparatus comprises a compressed air container from which breathing gas, usually compressed air, may be obtained for a short duration of time. It has been found that in many emergency situations a small amount of air, sufficient to last for about two minutes, is all that is necessary for survival. Breathing devices may be used in emergencies that occur in any environment, including, for example, fire, gas leakage, underwater crash and inspection of underwater boat damage.
Emergency breathing devices are particularly important to aircraft pilots and scuba divers. For example, in the event of helicopter crash into water, a portable breathing apparatus can provide sufficient air to enable a user involved in the crash to extract himself from the wreckage and swim to the surface. To provide easy access, the device may be stored inside the pocket of a typical flight suit often worn by military pilots. Thus, a pilot equipped with emergency breathing apparatus may quickly reach into his flight suit pocket, pull out the device, place the mouthpiece to his lips and start breathing.
Similarly, in another exemplary application, a portable breathing device can be of critical importance in the event that a scuba diver runs out of air. The breathing device can provide the extra breath of air necessary for the diver to swim up to the surface.
One such previously available device, of the type shown in U.S. Pat. No. 251,622, has a scuba type breathing regulator at the top and a pressurized cylinder connected thereto. The regulator has a supply valve for turning the device on and off. The supply valve when turned on allows air from within the cylinder to be supplied to the regulator valve. The supply valve is manually turned on and off by a knob. The regulator also has a port to facilitate refilling of the pressurized cylinder. This port is located proximate the supply valve. The port is sealed with a plug. The plug is knurled and has a central groove to facilitate removal. The plug also has a centrally located, spring loaded pin which acts as a pressure indicator. When the cylinder has a sufficient level of compressed air and the supply valve is open the pin will pop up indicating that the cylinder is full. Otherwise the top of the pin will remain flush with the bottom of the groove. A mouthpiece similar to the type used in scuba gear is used to inhale air from within the cylinder as regulated by the breathing regulator.
Although this device has been proven effective in saving lives, it has several significant disadvantages. In an emergency situation, it is desirable to have a breathing device that operates immediately upon inhaling so the user does not waste time fumbling with knobs in a panic situation. As discussed above, in order to use the currently available device, a user must first manually turn on the supply valve prior to using it. In order to avoid the need to take this extra step in an emergency, pilots, for example, in their pre-flight check list, are often required to manually turn on the supply valve prior to taking off. During the lifetime of the device, it is likely that the supply valve will be turned on and off repeatedly by users. This constant movement of the seal within the supply valve increases the likelihood of leakage through the seal. Further during flights and other activities where the supply valve is on, the other seals in the breathing regulator, including the dynamic seals of the regulator valve itself, are subjected to the full pressure of the air in the pressured cylinder. This provides additional opportunity for leakage and consequent failure.
Another disadvantage is that a user may test to see if the device works by allowing a little air to escape through the regulator valve. While doing so, the user has to be careful to limit the outflow, otherwise the device requires refilling. Refilling the apparatus with compressed air is undesirable in view of the time wasted and additional support equipment such as compressors, for example, which are required for the task. Further in order to test for air pressure, it is required that the supply valve be turned on so that the position of the pin on the supply plug can be checked. This type of constant manipulation of the device encourages idle tampering which can lead to malfunctioning of the unit.
Another disadvantage is that the mouthpiece in such a device is exposed and thus prone to accumulate dirt in the mouthpiece requiring a replacement. Additionally an exposed mouthpiece allows foreign objects to accumulate in the breathing chamber.
Prior to using such a device, some form of training is necessary. Without training it may not be readily apparent to a user how to operate such a device. For example, it is necessary for a user to learn how to turn the supply valve on, read the pressure indicator and to test the device prior to use.
These devices, although small, could in some cases get in the way of a person's movement. For example, the smallest currently available breathing device has a cylinder that is 11 inches long and an overall length of 131/2 inches including the breathing regulator portion. This device is comfortably accommodated within a pocket of a typical flight suit vest worn by many aircraft pilots. It is desirable to have the apparatus positioned at a tilt when placed in the pocket. A tilted position helps prevent injury to the pilot's head if he slumps over due to the impact of a crash. However, in some cases, especially for a person with a small torso, the apparatus cannot be tilted enough because of its size. Thus, under some circumstances an airman might hit his chin on the device in a crash. Further a smaller device is necessary in order to be practical for use by passengers of an aircraft. Accordingly, a more compact size breathing apparatus is desirable.